South Korea's ongoing row with Japan over the latter's trade restrictions in apparent retaliation for a court ruling on wartime forced labor is entering a new phase, after U.S. President Donald Trump said he would help resolve tensions between Seoul and Tokyo if the two countries needed him to do so.It is a good thing that Trump hinted at a mediating role to stop the situation from worsening, given he could be the only world leader to whom Japanese Prime Minister Shinzo Abe listens.Speaking to the White House press corps, Friday, Trump said South Korean President Moon Jae-in had asked if he could mediate between Seoul and Tokyo."It's like a full-time job getting involved between Japan and South Korea," Trump said, adding that he would be there only if the two countries need him. This was Trump's first comment on the matter.Trump's remarks could be interpreted as pressuring Abe to embrace dialogue with Seoul to seek a diplomatic solution to the worsening spat between his two main East Asian allies. Considering that South Korea has been seeking mediation by the U.S., while Japan is being cynical about it, the fact that Trump brought up its possibility could be a partial victory for Seoul. However, it would have been difficult for Trump just to sit back and watch, because tensions between the U.S. allies are developing into a possible threat to the security alliance in Northeast Asia. U.S. National Security Adviser John Bolton's visit to Japan and South Korea this week should be understood in this regard. Bolton is expected to visit Seoul for two days from Tuesday after talks with Japanese officials in Tokyo.We note that Trump's reaction came after Moon's security aides indicated earlier that Seoul could consider whether to renew a military intelligence-sharing pact with Japan. The General Security of Military Information Agreement (GSOMIA), signed in 2016 between Seoul and Tokyo to counter threats from North Korea, is renewed automatically every year as long as there is no complaint from either side 90 days before the end of its extendable one-year period.Whether to keep the intelligence pact with Japan was also a key discussion topic at Moon's meeting with the leaders of major political parties at Cheong Wa Dae last week.Japan will reportedly make a decision this week on whether to remove South Korea from a "white list" of 27 countries that receive preferential treatment for trade with Japan. If Korea was delisted, it would have far-reaching repercussions on bilateral trade and beyond. Then the fate of the GSOMIA would become uncertain because it would be strange for Korea to share military intelligence with a country in which it has lost trust.